iginiton timing questions

***Update*** Well this is what I came up with, when I got this engine running initially, when I setup the init timing I did a rookie move and left the vac advanced hooked up. Car runs good now that I have the timing right on it seems and my carbueration issues are gone. Since a recomendation I seen in a lot of tuning threads on this forum is to run with out the vac advance I plugged it up as well.

This is how I have always timed a car. I dunno where I learned this from, it maybe some BS way I came up with on my own when I was a kid and its just always seemed to get me there. So feel free to pick it apart and tell me the errors of my way, because I wouldn't mind knowing how to go about doing it better. Basically I would start with some init timing from my experience with LA small block engines I have found usually starting at 15 or 16 degrees is a good place to start and go up from there. Than I tune the carb for idle. Than I would just rev it up and go by sound and feel basically till it felt right but that only usually got me so close. Than I would take it out on the road and see what it was really doing under load and just kinda played with it till it felt good.

As for my distro being a "smog" distro I kinda doubt it or someone already change the springs out to lighter ones. Keeping the timing gun going and reving the engine to maybe 2000 or so, the timing seems to advance out very quickly. So this brings me back to my original questions I started this thread with or maybe I am asking the wrong questions. We known the ini timing but we don't know the mechanical timing. How can I go about finding out how much mechanical advance I have in the distro. Also for the springs are they marked in any sort of way where we can tell if they are lighter or heavier?

On a side note to help me figure this all out. I have a 360 thats fairly built up with a FBO system. When they built it for me they took the specs of engine and car and mechanically built it for those specs and gave me a data sheet that told what to set the init timing (20) than the total (34) and it should all be in at 3100rpm. So that would mean my distro on that engine has 14 degrees of mechanical. I have no idea what the curve is but I can tell you it doesn't seem the mechanical kicks in as fast as the one on the other engine. So my question is how did they come up with these numbers? I have tested trying to squeeze more timing and either the change isn't even noticeable or you get to a point where the change starts to effect how it acts in a negative way so it seems to me they have it nailed in pretty good.